Repeatability Study on Non-rigid Registration for DCE-MRI Measurement of Solitary Pulmonary Nodule

Objective:To investigate the repeatability before and after non-rigid registration in dynamic contrast-enhanced MRI quantitative analysis of solitary pulmonary nodules. Methods:Twenty-seven solitary pulmonary nodules underwent DCE-MRI examination on a 1.5 Tesla MR scanner. OmniKinetics software was applied with non-rigid registration of DCE-MRI. Two radiologists measured DCE-MRI quantitative parameters before and after the registration twice:capacity transfer constant (k^trans), rate constants (k_ep), extravascular extracellular space volume ratio (v_e), measured twice two weeks apart. The Bland-Altman analysis and Intraclass correlation coefficient (ICC) were used to assess the reproducibility of the quantitative parameters of inter- and intra-observer agreement. Result:The same reader measured twice, the value of ICC were 0.962 (k^trans), 0.736 (k_ep), 0.708 (v_e) before registration, and after were 0.983, 0.962, 0.834, respectively. After registration quantitative parameters were higher than before. After registration repeatability of k^trans, k_ep, v_e measurement (1.6%, 13.9%, 4.3%) better than before (4.8%, 33.5%, 9.6%). Between different readers, the value of ICC were 0.945 (k^trans), 0.760 (k_ep), 0.931 (v_e) before registration, and after were 0.988, 0.962, 0.976, after registration quantitative parameters were also higher than before. After registration repeatability of k^trans, k_ep, v_e measurement (1.8%, 13.7%, 13.1%) better than before (3.9%, 35.7%, 20.1%), respectively. Conclusion:Non-rigid registration technique can improve the repeatability of the measurement of solitary pulmonary nodule DCE-MRI quantitative parameters.